Modularized resistance unit

ABSTRACT

A modularized electrical resistance unit for use in connection with high-voltage systems which comprises a casing body, a support boss mounted within the casing body, a resistance carrier mounted on the support boss and disposed within the casing body, and encapsulating material completely encapsulating the resistance carrier including the peripheral edges thereof. The casing body is provided with an enlarged chamber surrounding the anode terminal to accommodate a greater volume of encapsulating material, and a barrier wall and corresponding slot arrangement between the high-voltage and low-voltage terminals.

United States Patent Dumas 1 Jan. 25, 1972 [54] MODULARIZED RESISTANCEUNIT 3,441,895 4/l969 Schwartz ..338/256 [72] Inventor: Christ J. Dumas,Forest View, Ill. Primary Examiner E A Goldberg [73] Assignee: AmericanPlasticraft Company, Chicago, At'or'ley-petherbridgev O'Neill & Lindgre"ill.

[57] ABSTRACT [22] Filed: Jan, 14, 1971 A modularized electricalresistance unit for use in connection PP N03 106,502 with high-voltagesystems which comprises a casing body, a support boss mounted within thecasing body, a resistance car- 52 us. Cl. ..338/256 174/52 PE 338/226SuPP)rt and dispmd 338/315 ing body, and encapsulating materialcompletely encapsulat- 511 rm. Cl ..H0lc 1 02 Si-glance carrierincluding Pe'iPhml edges 5s| Field of Search ..338/226 256 275 315- Thecasing is Pmvided with enlatged 336/96. 174/52 ,1 chamber surroundingthe anode terminal to accommodate a greater volume of encapsulatingmaterial, and a barrier wall 56] References Cited and corresponding slotarrangement between the high-voltage and low-voltage terminals.

10 Claims, 6 Drawing Figures PATENTEDJANZSIQYZ 3.638.161

SHEET 1 8F 2 INVENTOR. CHRIST J. DUMAS ATTORNEYS.

PATENTEB JANZSISYZ 3,638,161

sum 2 er 2 INVENTOR CHRIST J. DUMAS PM, 77.014 BY ATTORNEYS.

MODULARIZEI) RESISTANCE UNIT BACKGROUND OF THE INVENTION This inventionis directed to an improved modularized resistance unit for use inconnection with high-voltage systems such as TV receivers, precipitrons,ignition systems, voltage control systems screen grid voltage systems inTV receivers, and the like. More specifically, this invention isdirected to a modularized resistance unit wherein the resistance carrieris mounted within the casing body so as to enable complete encapsulationof the resistance carrier and the resistance element carried therebyincluding the peripheral edges thereof, and wherein the resistancecarrier is prevented from either lateral, circumferential or othermovement when mounted, thereby to increase the high-voltage breakdowncharacteristics of the resistance unit. In addition, the presentinvention provides an improved modularized resistance unit wherein adistinct barrier is provided between the high-voltage and low-voltageterminals for the purpose of increasing the breakdown voltagetherebetween, as well as providing an increased anode terminal areachamber which thereby further improves the corona start voltage and thehigh-voltage discharge or breakdown voltage of the modularizedresistance unit.

Modularized resistance units are known in the prior art. For example,there is disclosed in US. Pat. No. 3,441,895, issued on Apr. 29, 1969 toJack Schwartz, a cermet resistance module which comprises a casing bodyhaving a resistance carrier carrying a resistance pattern depositedthereon disposed within the casing body, wherein the casing body isprovided with a plurality of peripheral shoulders upon which theresistance carrier rests, and including encapsulating material which isinjected into the casing body after the resistance carrier has beenmounted therein in order to engulf and encapsulate the resistancecarrier as well as the resistance element carried thereby. Whileresistance modules of the type set forth in the aforementioned patenthave met with a fair modicum of success, nevertheless, certaindifiiculties have been experienced with such modules.

One such problem resides in the fact that complete encapsulation cannotbe accomplished due to the fact that peripheral shoulders are providedwithin the casing body upon which the resistance carrier is carried. Inthis manner, the encapsulating material is not capable of completelyengulfing the peripheral edges of the resistance carrier and thisconstruction provides a very easy breakdown path during abnormalhighvoltage or arcing phenomena.

Another problem arises by virtue of the fact that during manufacture ofsuch a resistance module, the resistance carrier is subject to movementwithin the casing body even after it has been placed upon the peripheralshoulders such that during the encapsulation process, the injection ofthe encapsulating material into the casing body may cause movement ofthe resistance carrier and thereby the resistance element depositedthereon effecting the electrical characteristics of the device.

Another problem resides in the fact that no distinct physical barrierhas been provided between the high-voltage and lowvoltage terminalwhereby the breakdown voltage as between these two terminals is at ahigh-stress level increasing the danger of electrical breakdown of theunit.

Finally, another problem exists by virtue of the fact that the areasurrounding bulk and volume of encapsulant thereby providing aconvenient breakdown voltage pathway.

Therefore, it is the principal object of the present invention toprovide an improved modularized resistance unit having a casing body, asupport boss mounted within the casing body extending upwardly from thebottom wall thereof for carrying a resistance carrier thereon, theresistance carrier having a re sistance element deposited thereon, thecasing body having en enlarged chamber adjacent the anode terminalthereof, and a quantity of encapsulating material completelyencapsulating and engulfing the resistance carrier and the resistanceelement carried thereby including the peripheral edges thereof in orderto provide a modularized resistance unit having increased high-voltagebreakdown characteristics and increased corona start voltage.

Another object of the present invention is to provide a modularizedresistance unit of the type set forth wherein a distinct physicalbarrier is provided between the high-voltage and low-voltage tenninalareas in order to further increase the high-voltage breakdowncharacteristics of the unit as a whole.

Still another object of the present invention is to provide amodularized resistance unit of the type set forth wherein the resistancecarrier is provided with a plurality of openings disposed therein toaccommodate the insertion therein of the stripped lead wires in order toimprove the mounting of the wires to the resistance element and therebyfurther increase the high-voltage breakdown characteristics of the unitand improve manufacturing efficiency.

Yet a further object of the present invention is to provide amodularized resistance unit of the type set forth wherein the means formounting the resistance carrier on the casing body comprises a supportboss mounted on the casing body and extending upwardly from the bottomwall thereof including a lower support section and a key member sectionthereon, and the resistance carrier provided with an opening designed tomate with the key member section of the support boss whereby once theresistance carrier is mounted upon the support boss, lateral,circumferential and other movement of the resistance carrier within thecasing body is prevented.

Further features of the invention pertain to the particular arrangementof the parts whereby the above-outlined additional operating featuresthereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the accompanying drawings, in which:

FIG. I is a top plan view of one embodiment of the modularizedresistance unit of the present invention;

FIG. 2 is a side cross-sectional elevational view of the invention takenin the direction of the arrows along the line 22 in FIG. 1;

FIG. 3 is an exploded fragmentary view showing the key member feature ofthe support boss and the corresponding mating section of the resistancecarrier which provides a mounting means for mounting the resistancecarrier upon the support boss;

FIG. 4 is a top plan view showing the casing body including the supportboss and the enlarged anode chamber of another embodiment of themodularized resistance unit of the present invention;

FIG. 5 is a top plan view showing still another embodiment of thepresent invention wherein the casing body is provided with a physicalbarrier wall and the resistance carrier is provided with a correspondingand mating slot to accommodate the barrier wall; and

FIG. 6 is a top plan view showing the resistance carrier in accordancewith one embodiment of the present invention and which further includesa series of three terminal-mounting holes for holding terminal leadwires in fixed relationship with respect to the resistance carrier.

With particular reference to FIG. 1 of the drawings, there isillustrated a modularized resistance unit generally referred to bynumeral 10. The unit 10 generally includes a series of four sidewalls 11extending upwardly from the peripheral edges of bottom wall 12 (see FIG.2), a pair of mounting lugs 13 extending laterally outwardly fromopposed sidewalls ll of the unit 10, each of the mounting lugs 13including a mounting opening 14 disposed therethrough to accommodate arivet, or bolt or other mounting device for mounting the unit 10 to thehigh-voltage system in which such unit is employed. The casing body ofthe unit 10 further includes a support boss generally referred to by thenumeral 15 (more particularly shown in FIG. 2), which includes a lowersupport section I6,

and a key member section 17 extending upwardly from the upper surface ofthe lower support section 16 for a short distance. A resistance carrier20 is generally shown in phantom in FIG. 1, which is provided with akey-mated opening 21, corresponding to the design of the key membersection 16. The resistance carrier 20 includes a resistance element (notshown) deposited thereon, and further includes a high-voltage terminal22, a low-voltage terminal 23, and a focus voltage terminal 24. Leadwire 25 is attached to high-voltage terminal 22 and extends outwardlytherefrom through strain relief 26, lead wire 27 is attached to alow-voltage terminal 23 and extends outwardly through strain relief 28,and lead wire 29 is attached to focus or tapped voltage terminal 24 andextends outwardly therefrom through a strain relief 30.

As shown in FIG. 2 of the drawings, once the resistance carrier 20 hasbeen suitably mounted by way of key-mated opening 21 upon key membersection 17, and the lead terminal wires 25, 27 and 29, respectively,have been suitably inserted through the corresponding strain reliefs 26,28 and 30, respectively, the casing body is filled with anencapsulatingmaterial 31 thereby to completely encapsulate and engulf the resistancecarrier 20 including the resistance element carried thereon.

In the preferred embodiment, once the resistance carrier 20 is suitablymounted upon the lower support section 16 by inserting the key membersection 17 through the key-mated opening 21, the upper section of thekey member section 17 is heat pressed downwardly in order to form arivet head 18 over the key-mated opening 21 thereby to firmly anchor theresistance carrier 20 in place. The manner of mounting the resistancecarrier 20 upon the support boss 15 including the lower support section16 and key member 17 thereof, is more clearly shown in FIG. 3 of thedrawings.

In the embodiment shown in FIGS. 1, 2 and 3 of the drawings, once themodularized resistance unit has been assembled and encapsulated asdescribed above, an electrically superior resistance module is obtained.By eliminating the peripheral supports for the resistance carrier 20,and by substituting therefore a single support boss for supporting theresistance carrier within the casing body, an increase in thehigh-voltage breakdown characteristics of the unit as a whole isrealized.

In FIG. 4 of the drawings, there is illustrated another embodiment ofthe present invention which provides an even more electrically efficientmodularized resistance unit. In this embodiment, there is shown a casingbody 35 comprising a bottom wall 36, a first sidewall 37, a secondsidewall 38, a third sidewall 39, and a fourth sidewall 40. Sidewall 39includes an outwardly extending flange portion 41 and the fourthsidewall 40 includes an outwardly extending flange portion 42, theoutwardly extending flange portion 41 and 42 being connected by aperipheral sidewall 43. Casing body 35 is further shown to include asupport boss 45 including a lower support section 46 and a key membersection 47. Finally, the casing body 35 is provided with mounting lugs48 each of which has a mounting opening 49 disposed therethrough formounting the casing body 35 to a supporting base (not shown). Inaddition, suitable strain reliefs 50 are provided as may be necessaryfor the terminal lead wires which extend outwardly from the terminals asdiscussed hereinabove. The height of peripheral wall 43 as well as theoutwardly extending flange portions 41 and 42, and peripheral wall 39extend upwardly for a height greater than the height of peripheral walls37, 38 and 39 from a point designated at 51 to apoint designated 52, asshown in FIG. 4 of the drawings.

An anode terminal wire collar 53 is provided extending laterallyoutwardly from peripheral wall 43. The collar 53 is of an extendedlength in order to provide a longer axial dielectric path to' groundthereby further improving the breakdown characteristics of the module.

The purpose for having an enlarged chamber area surrounding the anode orhigh-voltage terminal of the modularized resistanceunit as assembled,and having an increased height in the sidewalls surrounding the anodechamber, is that once the resistance carrier is mounted within thecasing body 35, and

' the encapsulating material injected therein, the high-voltagebreakdown characteristics of the resistance unit as a whole is greatlyincreased. This increase in the high-voltage breakdown characteristicsis the result of the mass and volume of the encapsulating material whichsurrounds the high-voltage terminal in the completed form.

In FIG. 5 of the drawings, there is illustrated the preferred embodimentof the invention wherein there is shown a casing body, generallydesignated by the numeral 55, including a bottom wall 56, a firstsidewall 57, a second sidewall 58, a third sidewall 59, and a fourthsidewall 60. The third sidewall 59 includes an outwardly extendingflange portion 61 and the fourth sidewall 60 includes outwardlyextending flange portion 62, the outwardly extending flange portions 61and 62, respectively, being connected by peripheral wall 63, in the samemanner as described with respect to the embodiment shown in FIG. 4 ofthe drawings. Once again, the peripheral wall 63, as well as theoutwardly extending flange portions 61 and 62 are of a height greaterthan the side walls 57 and 58 from a point designated at 64 along thirdsidewall 59 to a point designated at 65along fourth sidewall 60. Casingbody 55 is further provided with a support boss 66 which is constructedin the same manner as the support bosses 15 and 45 described withrespect to FIGS. 1, 2, 3 and 4 of the drawings. Casing body 55 is alsoprovided with suitable strain reliefs 67 in order to accommodate thecorresponding lead wires which extend from the associated terminals.

Casing body 55 is further provided with a barrier wall 70 which extendsfrom the third sidewall 59 inwardly toward the central region of thecasing body 55, the barrier wall 70 being integral with the thirdsidewall 59 as well as the bottom wall 56 of the casing body 55.

In FIG. 6 of the drawings, there is illustrated the resistance carrier,generally referred to by numeral 75, which is particularly adapted foruse in connection with the casing body 55 illustrated in FIG. 5 of thedrawings. The outer dimensions of resistance carrier are slightly lessthan the inner dimensions of the casing body 55, whereby the resistancecarrier 75 may be positioned within casing body 55. Resistance carrier75 is shown to include a key-mated mounting opening 76, which isdesigned to mate to the corresponding key member section of support boss66 in the manner depicted in FIG. 3 of the drawings. The resistancecarrier 75 further includes a slotted section 77 which extends inwardlyfrom the peripheral edge of the resistance carrier 75 for a distancesufficient to accommodate barrier wall 70. Finally, the resistancecarrier 75 is provided with a series of three lead wire mountingopenings 78 disposed therethrough which facilitates the mounting of thecorresponding lead wires to the resistance carrier 75.

The resistance carrier is generally formed of a nonconductive substrateusually fabricated from a material such as aluminum or steatite,although glass and other ceramics may be utilized, whereupon aresistance element, such as cermet, is deposited thereon. The resistancematerial, e.g., cermet, is deposited on the ceramic substrate in narrowstrips which have a specific resistance per unit length. The substrateis then heated in order to permanently bond the cermet thereto. Theresistance material, prior to encapsulation, may be further protected bycoating such material with an electrical insulator, such as blue diallylphthalate, or other suitable materials known in the art.

In the manufacture of the preferred embodiment of the modularizedresistance unit referred to in FIGS. 5 and 6 of the drawings, the casingbody 55 including the peripheral walls 57, 58, 59, 60, and the outwardlyextending flange portions 61, 62, respectively, as well as theconnecting peripheral walls 63, barrier wall 70, support boss 66, andthe strain reliefs 67, are all formed as an integral unit or as a singlepiecemold. The preferred material for such casing bodies is a plastic ofextremely low electrical conductivity. The resistance carrier 75 isformed in the manner indicated hereinabove, and the embodiment shown inFIG. 6 of the drawings is the preferred embodiment for use in connectionwith the casing body 55 shown in FIG. 5 of the drawings. The resistancecarrier 75 having the I resistance element deposited thereon is suitablypositioned within the casing body 55 by inserting the key member sectionof the support boss 66 through the key-mated mounting opening 76 therebyto securely position the resistance carrier 75 within the casing body55. The lower surface of the resistance carrier 75 rests against theupper surface of the lower support section of the support boss 66 in amanner depicted in FIG. 3 of the drawings. By having a key membersection and a-keymated mounting opening on the support boss and theresistance carrier, respectively, lateral, circumferential and all otherforms of movement of the resistance carrier 75 with respect to thecasing body 55 is substantially eliminated. Hence, greater economics interms of manufacturing are effected in this manner since the number ofrejects is substantially reduced due to the fact that accurate aligningmay be done by a relatively unskilled operator during the positioningoperation. The appropriate lead wires are inserted through the wiremount openings 78 disposed in a resistance carrier 75, and once again,this construction provides for a more economical manufacturing operationas well as improving the electrical characteristics of the module. Thatis, once the terminal wires have been suitably stripped, the ends of thewires are inserted through the openings 78 and thereby firmly held inposition while the operator effects the soldering of the wire to theresistance carrier 75.

Once the terminal lead wires have been suitably soldered to theresistance carrier 75, and the resistance carrier 75 accuratelypositioned within the casing body 55, the encapsulating material is theninjected into the casing body in order to completely engulf and encasethe resistance carrier 75 including the resistance material depositedthereon. In this position, barrier wall 70 is fitted in the slottedsection 77 of the resistance barrier 75, the electrical reasons beingmore fully described hereinafter. Of course, prior to encapsulation, thelead wires have been suitably threaded through corresponding strainreliefs such that once the encapsulating material hardens' within thecasing body, the modularized resistance unit is ready for installationin a suitable high-voltage system.

The electrical circuitry involved in modularized resistance units of thetype described herein, as well as the materials of which the variouselements of such a unit are composed, are well known in the art asmanifested by US. Pat. No. 3,44l ,895, referred to hereinabove, as wellas other prior art patents. Hence, such details are not deemed necessaryin connection with the improvements dealt with in the present invention.However, the construction of the present invention, especially thepreferred embodiment thereof, results in certain very distinctelectrical and manufacturing improvements over such prior art devices aswill be more fully explained hereinafter.

In accordance with the description of the improved modularizedresistance unit of the present invention, it will be appreciated thatone of the principal features provided by the present invention is thecomplete encapsulation and engulfment'of the resistance element carriedby the resistance carrier within the casing body. By providing a singlesupport boss within the casing body upon which the resistance carrier issupported and carried, one can obtain complete encapsulation by theencapsulating material of the resistance element. It will be furtherappreciated that by the removal of the peripheral shoulders as indicatedin the prior art devices, several highvoltage breakdown pathways areeliminated. In addition, this type of construction increases the coronastart voltage to a higher value, on the order of 33 percent.

Present modularized resistance units have a corona start voltage ofaround 30 kv. whereas the corona start voltage of the preferredembodiment of the present invention has a corona start voltage of about40 kv. on the average value basis. Hence, the dielectric strength of themodularized resistance unit is increased by not only the bulk, but alsothe volume provided by the increased amount of encapsulating materialsurrounding the resistance element. This result is obtained by firstproviding for the complete encapsulation as mentioned above, andsecondly, by increasing the height of the peripheral walls around theanode or high-voltage area thereby to provide an even greater amount ofbulk and volume of encapsulating material in and about the high-voltagearea. l-Ience, what is basically achieved is an increase in theintrinsic volumetric and conformal coverage of the resistance elementthereby increasing the high-voltage breakdown characteristics of theunit as a whole. While improved results are obtained with the embodimentof this invention as shown in FIGS. 1 and 2 of the drawings, even betterresults are obtained by the preferred embodiment shown in FIGS. 4 and 5of the drawings.

With particular reference to the embodiment shown in FIG. 5 of thedrawings, further improvement in the high-voltage breakdowncharacteristics of the module unit are obtained by virtue of the barrierwall 70 formed integrally with the casing body 55 which is injuxtaposition with the slot 77 formed in a resistance carrier 75. Thebarrier wall 70 provides a distinct physical barrier between thehigh-voltage terminal and the low-voltage terminal thereby to prevent anelectrical breakdown and leakage pathways as between these twoterminals. This results in longer life and reliability of the modulesystem.

In addition, this structure limits and substantially eliminates spuriouscorona voltages which are generated between the aforementioned twoterminals, thereby eliminating unwanted pulse interferences generated bycorona discharges. It will be appreciated that a similar result isobtained if the resistance carrier 75 having a slot 77 is utilized evenwithout a barrier wall 70 in the casing body 55 since without thebarrier wall, upon encapsulation of the resistance carrier having theresistance element deposited thereon, encapsulating material will nestin the slot 77 thereby similarly providing a physical barrier andimproving the breakdown voltage as between the two terminals. However,it has been found that by not only having the slot 77, but also thebarrier wall 70 nested therein, an improved physical barrier is achievedand the breakdown voltage characteristics of the module system aregreatly improved.

For example, a modularized resistance unit which is not encapsulatedwith encapsulating material and which does not have a slot in theresistance carrier and lacks a barrier wall will have a breakdownvoltage as between the anode terminal and the cathode terminal at about20 kv. A modularized resistance unit lacking encapsulation byencapsulating material and provided with a slot in the resistancecarrier but no barrier wall will have a breakdown voltage at aboutbetween 22 and 23 kv., the reason for the slight increase being thatthere is an air dielectric path interrupting the breakdown path asbetween these two terminals thereby improving the breakdown voltage. Aresistance module which lacks encapsulating material but is providedwith a slot in the resistance carrier and with a barrier wall disposedtherebetween will have a breakdown voltage at about 33 kv. for thereason that there is now provided a physical barrier which breaks downin the discharge path thereby further improving the breakdown voltage.As compared to the above units, a modularized resistance unit havingsubstantially complete encapsulation but with no barrier wall and noslot in the resistance carrier, e.g., the type of modularized resistanceunit as disclosed in US. Pat. No. 3,441,895, will have a breakdownvoltage on the order of about 50 kv. However, the modularized resistanceunit of the present invention further improves upon the breakdownvoltage characteristics by as much as 30 percent. The embodiment asshown in FIG. 5 of the drawings having complete encapsulation by theprovision of a single support boss and including a slot in theresistance carrier and a barrier wall disposed therebetween will have abreakdown voltage on the order of about 65 kv., thereby showing anincrease of approximately 30 percent improvement in the breakdownvoltage over prior art devices.

As was mentioned above, not only is the breakdown voltage of the unit asa whole improved by virtue of the construction of the present invention,but also, the reliability and longevity of the unit is improved while inuse.

With particular reference to FIG. 6 of the drawings, there is shown aresistance carrier 75 which is shown to include a series of three wiremounting openings 78 disposed therein. The openings 78'are provided inapproximately the centerline of the metallized connecting areas wherewires are attached for connection to the respective resistance patterns.These openings 78 are used as added strength where the partiallystripped lead wire is allowed to enter the opening 78 and allowed tofully bottom and then bent over and around the resistance carrier beforethe solder is applied. In this manner, lateral and axial strain reliefto the lead is provided, and an improvement of the corona startcharacteristics is accomplished, which is important in high-voltagemodules where corona starts or corona itself could be detrimental to theoperation of the unit.

From a manufacturing standpoint, the openings 78 have additional valuein that the operator may insert the stripped terminal lead wires throughthe openings 78 until the wires bottom, and then solder applied. Thiseliminates the step of requiring the operator to position the wires andmanually hold the wire in position during the soldering operation.Obviously,

. if the operator does not accurately position the terminal wire on theresistance pattern, then the chances for additional breakdown pathwaysor leakage is greatly enhanced. Hence, not only does one obtain a morerounded, conformable and well uniform solder pattern area which resultsin a low corona connection of the terminal lead wires to the resistanceelement, but the manufacturing steps involved in assembling such a unitis rendered more efficient.

The module of the present invention can be utilized in many capacities.For example, such resistance module units can be used as a bleedersystem to effect a constant impedance swamping a high-voltage powersupply, thereby allowing the system to become somewhat voltagestabilized. Any overvoltage ripple or spikes which may reach voltagesexceeding 60 kv. during the high-voltage arcing event in the unit, willcause the resistance module to act as a dampening device to quench orresist the high-voltage spikes or overvoltage and limit suchovervoltages to about between and percent of the normal quiesent appliedDC voltage. Such bleeders may also be used for focus application in TVreceivers and will have the same characteristics related above withfurther overvoltage protection by virtue of the fact that since thevoltage is impressed between the anode and focus taps, the overvoltageevent will be further restricted because the focus tap of the picturetube is fully tracking or riding in direct relation to the overvoltagecausing the focus impedance or resistance from focus tap to ground toload down the high voltage thereby to cause less cascaded arcing and amuch quicker reaction to the arcing cleanup after an arcing phenomenon.

In addition to use in connection with bleeders in a TV receiver system,such modular resistance units also have use in precipitrons, in ignitionsystems, and voltage control systems, as well as screen grid voltagesystems in TV receivers. Such units cause a constant idling current toflow from the power supply to the ground terminal, hence improvedquieting of power supply operation is accomplished.

Hence, in accordance with the present invention, there has been providedan improved modularized resistance unit which substantially increasesthe breakdown voltage characteristics of the unit as a whole byminimizing leakage pathways or discharge breakdown pathways in the unit,minimizes the corona effect, improves the intrinsic module corona startvoltage, and provide a more economic structure from a manufacturingstandpoint. The modularized resistance unit of the present inventionachieves a greatly improved electrical characteristic because theencapsulating material is allowed to completely encapsulate theresistance carrier and the resistance element patterndeposited thereonby the provision of a single support boss for carrying the resistancecarrier. The support boss further functions to securely position theresistance carrier in a predetermined position minimizing andsubstantially eliminating lateral, circumferential, as well as all otherforms or directions of movement of the resistance carrier within thecasing body, especially during the encapsulation operation. ln thismanner, more uniform results are obtained on a production basis where aplurality of units must be quickly and efficiently encapsulated duringthe manufacturing process. Furthermore, by the provision of terminalwire openings in the resistance carrier, the manufacturing process isfurther improved by enabling the operator to accurately position thewires and have the wire automatically held in place prior to thesoldering operation. Therefore, an improved modularized resistance unitsatisfying the objects and advantages set forth hereinabove has beenprovided by virtue of this'invention.

While there has been described what is at present considered to bepreferred embodiments of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and scope of the invention.

lclaim:

1. In a resistance module having a casing body including a bottom wallbounded by peripheral sidewalls upstanding therefrom, at least onestrain relief projection on the casing body, a resistance carrier, aresistance element including a pattern of cermet resistance materialbonded to and carried by said resistance carrier, said resistancecarrier having dimensions smaller than the internal dimensions of thecasing body so as to be positionable within said casing body, theresistance element including electrical conductors connected thereto andextending therefrom which are engaged by the strain relief to firmlylock the electrical conductors in place when the resistance element ispositioned within the casing body, and an encapsulating hardenableliquid material for encapsulating and engulfing the resistance elementafter positioning the samevwithin the casing body, the improvementcomprising mounting means for mounting said resistance carrier withinsaid casing body including a support boss-rnounted on said casing bodyand extending upwardly from the bottom wall thereof and positionedwithin the area bounded by the peripheral sidewalls thereof, and anopening provided in said resistance carrier, said opening havingdimensions substantially equal to said support boss, whereby saidresistance carrier may be mounted on and supported by said support bossthrough said opening thereby to enable the encapsulating hardenableliquid material to completely encapsulate the resistance element carriedby said resistance carrier thereby improving the dielectriccharacteristics of said module.

2. The resistance module as set forth in claim 1 above, wherein saidsupport boss includes a lower support section extending upwardly fromthe bottom wall of said casing body for a distance less than the heightof the sidewalls thereof and an upper key member portion extendingupwardly from the upper surface of said lower support portion, said keymember portion being smaller in overall diameter than the diameter ofsaid lower support portion, and said opening in said resistance carrierbeing formed to mate with said key member portion of said support bosswhereby said resistance carrier may be positioned within said casingbody by inserting said key member portion through said opening andhaving the lower surface of said resistance carrier supported by theupper surface of said lower support portion.

3. The resistance module as set forth in claim 2 above, wherein said keymember portion extends completely through said opening in saidresistance carrier, the upper portion of said key member portion beingcrimped to form a rivet head over the portion of said resistance carriersurrounding said opening thereby to hold said resistance carrier firmlyin position.

4. In a resistance module having a casing body including a bottom walland four sidewalls upstanding therefrom, at least one strain reliefprojection on the casing body, a resistance element including a patternof cermet resistance material bonded to a slablike resistance carrier,the resistance carrier having dimensions smaller than the internaldimensions of the casing body so as to be positionable within the casingbody, the resistance element including electrical conductors connectedthereto and extending therefrom which are engaged by the strain reliefto firmly lock the electrical conductors in place when the resistanceelement is positioned within the easing body, and an encapsulatinghardenable liquid material for encapsulating and engulfing theresistance element after positioning the same within the casing body,the improvement comprising a support boss formed integrally with saidcasing body and extending upwardly from the bottom wall thereof andpositioned within the area bounded by the sidewalls thereof, saidcentral support boss extending upwardly for a distance less than theheight of the sidewalls of the casing body and having a flattenedsurface on the upper end thereof, a key member portion extendingupwardly from the upper surface of said central support boss for adistance whereby the. total height of said central support boss and saidkey member portion is substantially equal to the height of the sidewallsof the casing body, and an opening disposed through said resistancecarrier, said opening being designed to mate with said key memberportion, whereby the resistance carrier may be mounted on said centralsupport boss and supported by the upper surface thereof by insertingsaid key member portion through said opening in the resistance carrierthereby to enable the encapsulating hardenable liquid material tocompletely encapsulate and engulf the resistance element bonded on theresistance carrier to improve the resistance characteristics of saidmodule.

5. A resistance module comprising a casing body including a bottom walland a plurality of sidewalls extending upwardly therefrom andperipherally thereabout to form a central chamber area, a portion ofeach of two adjacent of said sidewalls including outwardly extendedportions, said outwardly extended portions being circumferentiallyconnected by a sidewall thereby to form a chamber radially offset fromsaid central chamber area, a support boss mounted on said casing bodyand extending upwardly from the bottom wall thereof and positionedwithin said central chamber area, a resistance carrier, a resistanceelement including a pattern of cermet resistance material carried bysaid resistance carrier, said resistance carrier having dimensionssmaller than the internal dimensions of the casing body so as to bepositionable within said central chamber area, at least one strainrelief projection on the casing body and extending outwardly therefrom,said resistance element including electrical conductors connectedthereto and extending therefrom which are engaged by said strain reliefto firmly lock said electrical conductors in place when the resistanceelement is positioned within the casing body, said resistance carrierbeing provided with an opening therethrough, said opening havingdimensions substantially equal to said support boss whereby saidresistance carrier may be mounted upon and supported by said supportboss by inserting said support boss through said opening, and anencapsulating hardenable liquid material encapsulating and engulfing theresistance element after positioning the same within the casing body,thereby to enable the encapsulating hardenable liquid material tocompletely engulf the resistance element bonded on said resistancecarrier improving the dielectric characteristics of said module.

6. The resistance module as set forth in claim 5, wherein saidresistance carrier is provided with a slot extending inwardly from aside edge thereof and terminating at a point adjacent to said openingdisposed through said resistance carrier.

7. The resistance module as set forth in claim 6, wherein said casingbody is provided with a barrier wall extending upwardly from the bottomwall thereof and extending from a sidewall thereof inwardly therefrom,said barrier wall being positioned so as to be in juxtaposition withsaid slot in said ceramic base when said resistance carrier ispositioned within said casing body.

8. The resistance module as set forth in claim 5, wherein said supportboss on said casing body includes a lower support section extendingupwardly from bottom wall of said casing body for a distance less thanthe height of the sidewalls thereof and having a flattened surface onthe upper end thereof, and an upper key member portion extendingupwardly from the upper surface of said lower support portion for adistance whereby the total height of said lower support section and saidkey member section is substantially equal to the height of the sidewallsof the casing body, and wherein said opening in said resistance carrieris designed to mate with the key member portion whereby said key memberportion is inserted through said opening and the lower surface of saidresistance carrier rests upon the upper surface of said lower supportportion of said support boss thereby to accurately position saidresistance carrier upon said support boss and prevent lateral,circumferential and other movement of said resistance carrier whenpositioned within said casing body.

9. The resistance module as set forth in claim 5, wherein said sidewallsforming said radially offset chamber have a height slightly greater thanthe height of the remaining sidewalls thereby to form an enlargedradially ofiset chamber.

10. The resistance module as set forth in claim 5 wherein saidresistance carrier includes a plurality of terminal wire mountingopenings disposed therethrough to accommodate the insertion of theterminal wire therein thereby to provide improved anchoring sites andsolder points for connecting the terminal wires to said resistanceelement.

Patent No. 3,638,161 Dated January 25, 1972 Inventor(s) Christ J. DumasIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column I, cancel lines 64-66 and insert the following: Finally, anotherproblem exists by virtue of the fact that the area surrounding the anodeor high voltage terminal lacks sufficient bulk and volume ofencapsulant, thereby providing a convenient breakdown voltage pathway.

Signed and sealed this 12th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM P0-1050 (10-69) uscoMM-oc 60376-P69 fi U.S. GOVERNMENTPRINTING OFFlCE I569 0-866-334.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3 638,161 Dated January 25, 1972 Inventor(s) Christ J. Dumas It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, cancel lines 64-66 and insert the following: Finally, anotherproblem exists by virtue of the fact that the area surrounding the anodeor high voltage terminal lacks sufficient bulk and volume ofencapsulant, thereby providing a convenient breakdown voltage pathway.

Signed and sealed this 12th day of December 1972 (SEAL) Attest:

EDWARD M.FLE TCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PC4050 (169) USCOMM-DC 60376-P69 U-S. GOVERNMENTPRINTING OFFICE 1 I959 O-'36G-3J4,

1. In a resistance module having a casing body including a bottom wallbounded by peripheral sidewalls upstanding therefrom, at least onestrain relief projection on the casing body, a resistance carrier, aresistance element including a pattern of cermet resistance materialbonded to and carried by said resistance carrier, said resistancecarrier having dimensions smaller than the internal dimensions of thecasing body so as to be positionable within said casing body, theresistance element including electrical conductors connected thereto andextending therefrom which are engaged by the strain relief to firmlylock the electrical conductors in place when the resistance element ispositioned within the casing body, and an encapsulating hardenableliquid material for encapsulating and engulfing the resistance elementafter positioning the same within the casing body, the improvementcomprising mounting means for mounting said resistance carrier withinsaid casing body including a support boss mounted on said casing bodyand extending upwardly from the bottom wall thereof and positionedwithin the area bounded by the peripheral sidewalls thereof, and anopening provided in said resistance carrier, said opening havingdimensions substantially equal to said support boss, whereby saidresistance carrier may be mounted on and supported by said support bossthrough said opening thereby to enable the encapsulating hardenableliquid material to completely encapsulate the resistance element carriedby said resistance carrier thereby improving the dielectriccharacteristics of said module.
 2. The resistance module as set forth inclaim 1 above, wherein said support boss includes a lower supportsection extending upwardly from the bottom wall of said casing body fora distance less than the height of the sidewalls thereof and an upperkey member portion extending upwardly from the upper surface of saidlower support portion, said key member portion being smaller in overalldiameter than the diameter of said lower support portion, and saidopening in said resistance carrier being formed to mate with said keymember portion of said support boss whereby said resistance carrier maybe positioned within said casing body by inserting said key memberportion through said opening and having the lower surface of saidresistance carrier supported by the upper surface of said lower supportportion.
 3. The resistance module as set forth in claim 2 above, whereinsaid key member portion extends completely through said opening in saidresistance carrier, the upper portion of said key member portion beingcrimped to form a rivet head over the portion of said resistance carriersurrounding said opening thereby to hold said resistance carrier firmlyin position.
 4. In a resistance module having a casing body including abottom wall and four sidewalls upstanding therefrom, at least one strainrelief projection on the casing body, a resistance element including apattern of cermet resistance material bonded to a slablike resistancecarrier, the resistance carrier having dimensions smaller than theinternal dimensions of the casing body so as to be positionable withinthe casing body, the resistance element including electrical conductorsconnected thereto and extending therefrom which are engaged by thestrain relief to firmly lock the electrical conductors in place when theresistance element is positioned within the casing body, and anencapsulating hardenable liquid material for encapsulating and engulfingthe resistance element after positioning the same within the casingbody, the improvement comprising a support boss formed integrally withsaid casing body and extending upwardly from the bottom wall thereof andpositioned within the area bounded by the sidewalls thereof, saidcentral support boss extending upwardly for a distance less than theheight of the sidewalls of the casing Body and having a flattenedsurface on the upper end thereof, a key member portion extendingupwardly from the upper surface of said central support boss for adistance whereby the total height of said central support boss and saidkey member portion is substantially equal to the height of the sidewallsof the casing body, and an opening disposed through said resistancecarrier, said opening being designed to mate with said key memberportion, whereby the resistance carrier may be mounted on said centralsupport boss and supported by the upper surface thereof by insertingsaid key member portion through said opening in the resistance carrierthereby to enable the encapsulating hardenable liquid material tocompletely encapsulate and engulf the resistance element bonded on theresistance carrier to improve the resistance characteristics of saidmodule.
 5. A resistance module comprising a casing body including abottom wall and a plurality of sidewalls extending upwardly therefromand peripherally thereabout to form a central chamber area, a portion ofeach of two adjacent of said sidewalls including outwardly extendedportions, said outwardly extended portions being circumferentiallyconnected by a sidewall thereby to form a chamber radially offset fromsaid central chamber area, a support boss mounted on said casing bodyand extending upwardly from the bottom wall thereof and positionedwithin said central chamber area, a resistance carrier, a resistanceelement including a pattern of cermet resistance material carried bysaid resistance carrier, said resistance carrier having dimensionssmaller than the internal dimensions of the casing body so as to bepositionable within said central chamber area, at least one strainrelief projection on the casing body and extending outwardly therefrom,said resistance element including electrical conductors connectedthereto and extending therefrom which are engaged by said strain reliefto firmly lock said electrical conductors in place when the resistanceelement is positioned within the casing body, said resistance carrierbeing provided with an opening therethrough, said opening havingdimensions substantially equal to said support boss whereby saidresistance carrier may be mounted upon and supported by said supportboss by inserting said support boss through said opening, and anencapsulating hardenable liquid material encapsulating and engulfing theresistance element after positioning the same within the casing body,thereby to enable the encapsulating hardenable liquid material tocompletely engulf the resistance element bonded on said resistancecarrier improving the dielectric characteristics of said module.
 6. Theresistance module as set forth in claim 5, wherein said resistancecarrier is provided with a slot extending inwardly from a side edgethereof and terminating at a point adjacent to said opening disposedthrough said resistance carrier.
 7. The resistance module as set forthin claim 6, wherein said casing body is provided with a barrier wallextending upwardly from the bottom wall thereof and extending from asidewall thereof inwardly therefrom, said barrier wall being positionedso as to be in juxtaposition with said slot in said ceramic base whensaid resistance carrier is positioned within said casing body.
 8. Theresistance module as set forth in claim 5, wherein said support boss onsaid casing body includes a lower support section extending upwardlyfrom bottom wall of said casing body for a distance less than the heightof the sidewalls thereof and having a flattened surface on the upper endthereof, and an upper key member portion extending upwardly from theupper surface of said lower support portion for a distance whereby thetotal height of said lower support section and said key member sectionis substantially equal to the height of the sidewalls of the casingbody, and wherein said opening in said resistance carrier is designed tomate with the key member portion whereby said key member portion isinserted through said opening and the lower surface of said resistancecarrier rests upon the upper surface of said lower support portion ofsaid support boss thereby to accurately position said resistance carrierupon said support boss and prevent lateral, circumferential and othermovement of said resistance carrier when positioned within said casingbody.
 9. The resistance module as set forth in claim 5, wherein saidsidewalls forming said radially offset chamber have a height slightlygreater than the height of the remaining sidewalls thereby to form anenlarged radially offset chamber.
 10. The resistance module as set forthin claim 5 wherein said resistance carrier includes a plurality ofterminal wire mounting openings disposed therethrough to accommodate theinsertion of the terminal wire therein thereby to provide improvedanchoring sites and solder points for connecting the terminal wires tosaid resistance element.